Self‐Driven Humidity Regulation via Hygroscopic Salt Cycling

ABSTRACT Indoor air quality plays a crucial role in human health and daily life. Humidity control materials (HCMs) have been developed to intelligently regulate indoor humidity in an energy‐efficient manner. However, there is an urgent need to explore new HCMs that offer more energy‐efficient humidity control solutions. In this study, a new humidity control method based on the release and recapture of hygroscopic salts has been developed based on a series of inorganic‐organic hybrid metal halides (IOMHs), namely [TEMA] 2 SbCl 5 ( 1 , TEMA = triethylmethyl ammonium), [AMIM] 3 SbCl 6 ( 2 , AMIM = 1‐allyl‐3‐methylimidazolium), and [TAAC] 4 SbCl 6 ·Cl ( 3 , TAAC = allyltrimethyl ammonium). The adsorption of water could trigger the release of A Cl from these A m SbCl n ( A = cation) IOMHs, generating the mixture of A 3 Sb 2 Cl 9 and A Cl. The hygroscopicity of released A Cl results in the high‐water adsorption capacity, which could reach up to 1.18 g g −1 by changing the release amount of A Cl. During the desorption process, the A Cl would be recaptured by A 3 Sb 2 Cl 9 , resulting in the A m SbCl n regeneration. Releasing energy can facilitate the unique self‐driven water desorption behavior superior to that of traditional HCMs. Practical evaluation tests in a real environment demonstrate that 2 could spontaneously and rapidly maintain indoor humidity levels between 40% and 70%.